/*
 * Copyright 2007 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*namespace com.google.zxing.qrcode.detector {*/

import DecodeHintType from './../../DecodeHintType'
import ResultPoint from './../../ResultPoint'
import ResultPointCallback from './../../ResultPointCallback'
import BitMatrix from './../../common/BitMatrix'
import FinderPattern from './FinderPattern'
import FinderPatternInfo from './FinderPatternInfo'
import Exception from './../../Exception'

/*import java.io.Serializable;*/
/*import java.util.ArrayList;*/
/*import java.util.Collections;*/
/*import java.util.Comparator;*/
/*import java.util.List;*/
/*import java.util.Map;*/

/**
 * <p>This class attempts to find finder patterns in a QR Code. Finder patterns are the square
 * markers at three corners of a QR Code.</p>
 *
 * <p>This class is thread-safe but not reentrant. Each thread must allocate its own object.
 *
 * @author Sean Owen
 */
export default class FinderPatternFinder {

  private static CENTER_QUORUM = 2;
  protected static MIN_SKIP = 3; // 1 pixel/module times 3 modules/center
  protected static MAX_MODULES = 57; // support up to version 10 for mobile clients

  private possibleCenters: FinderPattern[]
  private hasSkipped: boolean
  private crossCheckStateCount: Int32Array

  /**
   * <p>Creates a finder that will search the image for three finder patterns.</p>
   *
   * @param image image to search
   */
  // public constructor(image: BitMatrix) {
  //   this(image, null)
  // }

  public constructor(private image: BitMatrix, private resultPointCallback: ResultPointCallback) {
    this.possibleCenters = []
    this.crossCheckStateCount = new Int32Array(5)
    this.resultPointCallback = resultPointCallback
  }

  protected getImage(): BitMatrix {
    return this.image
  }

  protected getPossibleCenters(): FinderPattern[] {
    return this.possibleCenters
  }

  public find(hints: Map<DecodeHintType, any>): FinderPatternInfo /*throws NotFoundException */ {
    const tryHarder: boolean = (hints !== null && hints !== undefined) && undefined !== hints.get(DecodeHintType.TRY_HARDER)
    const pureBarcode: boolean = (hints !== null && hints !== undefined) && undefined !== hints.get(DecodeHintType.PURE_BARCODE)
    const image = this.image
    const maxI = image.getHeight()
    const maxJ = image.getWidth()
    // We are looking for black/white/black/white/black modules in
    // 1:1:3:1:1 ratio; this tracks the number of such modules seen so far

    // Let's assume that the maximum version QR Code we support takes up 1/4 the height of the
    // image, and then account for the center being 3 modules in size. This gives the smallest
    // number of pixels the center could be, so skip this often. When trying harder, look for all
    // QR versions regardless of how dense they are.
    let iSkip = Math.floor((3 * maxI) / (4 * FinderPatternFinder.MAX_MODULES))
    if (iSkip < FinderPatternFinder.MIN_SKIP || tryHarder) {
      iSkip = FinderPatternFinder.MIN_SKIP
    }

    let done: boolean = false
    const stateCount = new Int32Array(5)
    for (let i = iSkip - 1; i < maxI && !done; i += iSkip) {
      // Get a row of black/white values
      stateCount[0] = 0
      stateCount[1] = 0
      stateCount[2] = 0
      stateCount[3] = 0
      stateCount[4] = 0
      let currentState = 0
      for (let j = 0; j < maxJ; j++) {
        if (image.get(j, i)) {
          // Black pixel
          if ((currentState & 1) === 1) { // Counting white pixels
            currentState++
          }
          stateCount[currentState]++
        } else { // White pixel
          if ((currentState & 1) === 0) { // Counting black pixels
            if (currentState === 4) { // A winner?
              if (FinderPatternFinder.foundPatternCross(stateCount)) { // Yes
                const confirmed: boolean = this.handlePossibleCenter(stateCount, i, j, pureBarcode)
                if (confirmed === true) {
                  // Start examining every other line. Checking each line turned out to be too
                  // expensive and didn't improve performance.
                  iSkip = 2
                  if (this.hasSkipped === true) {
                    done = this.haveMultiplyConfirmedCenters()
                  } else {
                    const rowSkip = this.findRowSkip()
                    if (rowSkip > stateCount[2]) {
                      // Skip rows between row of lower confirmed center
                      // and top of presumed third confirmed center
                      // but back up a bit to get a full chance of detecting
                      // it, entire width of center of finder pattern

                      // Skip by rowSkip, but back off by stateCount[2] (size of last center
                      // of pattern we saw) to be conservative, and also back off by iSkip which
                      // is about to be re-added
                      i += rowSkip - stateCount[2] - iSkip
                      j = maxJ - 1
                    }
                  }
                } else {
                  stateCount[0] = stateCount[2]
                  stateCount[1] = stateCount[3]
                  stateCount[2] = stateCount[4]
                  stateCount[3] = 1
                  stateCount[4] = 0
                  currentState = 3
                  continue
                }
                // Clear state to start looking again
                currentState = 0
                stateCount[0] = 0
                stateCount[1] = 0
                stateCount[2] = 0
                stateCount[3] = 0
                stateCount[4] = 0
              } else { // No, shift counts back by two
                stateCount[0] = stateCount[2]
                stateCount[1] = stateCount[3]
                stateCount[2] = stateCount[4]
                stateCount[3] = 1
                stateCount[4] = 0
                currentState = 3
              }
            } else {
              stateCount[++currentState]++
            }
          } else { // Counting white pixels
            stateCount[currentState]++
          }
        }
      }
      if (FinderPatternFinder.foundPatternCross(stateCount)) {
        const confirmed: boolean = this.handlePossibleCenter(stateCount, i, maxJ, pureBarcode)
        if (confirmed === true) {
          iSkip = stateCount[0]
          if (this.hasSkipped) {
            // Found a third one
            done = this.haveMultiplyConfirmedCenters()
          }
        }
      }
    }

    const patternInfo: FinderPattern[] = this.selectBestPatterns()
    ResultPoint.orderBestPatterns(patternInfo)

    return new FinderPatternInfo(patternInfo)
  }

  /**
   * Given a count of black/white/black/white/black pixels just seen and an end position,
   * figures the location of the center of this run.
   */
  private static centerFromEnd(stateCount: Int32Array, end: number /*int*/): number/*float*/ {
    return (end - stateCount[4] - stateCount[3]) - stateCount[2] / 2.0
  }

  /**
   * @param stateCount count of black/white/black/white/black pixels just read
   * @return true iff the proportions of the counts is close enough to the 1/1/3/1/1 ratios
   *         used by finder patterns to be considered a match
   */
  protected static foundPatternCross(stateCount: Int32Array): boolean {
    let totalModuleSize = 0
    for (let i = 0; i < 5; i++) {
      const count = stateCount[i]
      if (count === 0) {
        return false
      }
      totalModuleSize += count
    }
    if (totalModuleSize < 7) {
      return false
    }
    const moduleSize: number/*float*/ = totalModuleSize / 7.0
    const maxVariance: number/*float*/ = moduleSize / 2.0
    // Allow less than 50% variance from 1-1-3-1-1 proportions
    return Math.abs(moduleSize - stateCount[0]) < maxVariance &&
        Math.abs(moduleSize - stateCount[1]) < maxVariance &&
        Math.abs(3.0 * moduleSize - stateCount[2]) < 3 * maxVariance &&
        Math.abs(moduleSize - stateCount[3]) < maxVariance &&
        Math.abs(moduleSize - stateCount[4]) < maxVariance
  }

  private getCrossCheckStateCount(): Int32Array {
    const crossCheckStateCount = this.crossCheckStateCount
    crossCheckStateCount[0] = 0
    crossCheckStateCount[1] = 0
    crossCheckStateCount[2] = 0
    crossCheckStateCount[3] = 0
    crossCheckStateCount[4] = 0
    return crossCheckStateCount
  }

  /**
   * After a vertical and horizontal scan finds a potential finder pattern, this method
   * "cross-cross-cross-checks" by scanning down diagonally through the center of the possible
   * finder pattern to see if the same proportion is detected.
   * 
   * @param startI row where a finder pattern was detected
   * @param centerJ center of the section that appears to cross a finder pattern
   * @param maxCount maximum reasonable number of modules that should be
   *  observed in any reading state, based on the results of the horizontal scan
   * @param originalStateCountTotal The original state count total.
   * @return true if proportions are withing expected limits
   */
  private crossCheckDiagonal(startI: number /*int*/, centerJ: number /*int*/, maxCount: number /*int*/, originalStateCountTotal: number /*int*/): boolean {
    const stateCount: Int32Array = this.getCrossCheckStateCount()

    // Start counting up, left from center finding black center mass
    let i = 0
    const image = this.image
    while (startI >= i && centerJ >= i && image.get(centerJ - i, startI - i)) {
      stateCount[2]++
      i++
    }

    if (startI < i || centerJ < i) {
      return false
    }

    // Continue up, left finding white space
    while (startI >= i && centerJ >= i && !image.get(centerJ - i, startI - i) &&
           stateCount[1] <= maxCount) {
      stateCount[1]++
      i++
    }

    // If already too many modules in this state or ran off the edge:
    if (startI < i || centerJ < i || stateCount[1] > maxCount) {
      return false
    }

    // Continue up, left finding black border
    while (startI >= i && centerJ >= i && image.get(centerJ - i, startI - i) &&
           stateCount[0] <= maxCount) {
      stateCount[0]++
      i++
    }
    if (stateCount[0] > maxCount) {
       return false
    }

    const maxI = image.getHeight()
    const maxJ = image.getWidth()

    // Now also count down, right from center
    i = 1
    while (startI + i < maxI && centerJ + i < maxJ && image.get(centerJ + i, startI + i)) {
      stateCount[2]++
      i++
    }

    // Ran off the edge?
    if (startI + i >= maxI || centerJ + i >= maxJ) {
       return false
    }

    while (startI + i < maxI && centerJ + i < maxJ && !image.get(centerJ + i, startI + i) &&
           stateCount[3] < maxCount) {
      stateCount[3]++
      i++
    }

    if (startI + i >= maxI || centerJ + i >= maxJ || stateCount[3] >= maxCount) {
      return false
    }

    while (startI + i < maxI && centerJ + i < maxJ && image.get(centerJ + i, startI + i) &&
           stateCount[4] < maxCount) {
      stateCount[4]++
      i++
    }

    if (stateCount[4] >= maxCount) {
      return false
    }

    // If we found a finder-pattern-like section, but its size is more than 100% different than
    // the original, assume it's a false positive
    const stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4]
    return Math.abs(stateCountTotal - originalStateCountTotal) < 2 * originalStateCountTotal &&
        FinderPatternFinder.foundPatternCross(stateCount)
  }

  /**
   * <p>After a horizontal scan finds a potential finder pattern, this method
   * "cross-checks" by scanning down vertically through the center of the possible
   * finder pattern to see if the same proportion is detected.</p>
   *
   * @param startI row where a finder pattern was detected
   * @param centerJ center of the section that appears to cross a finder pattern
   * @param maxCount maximum reasonable number of modules that should be
   * observed in any reading state, based on the results of the horizontal scan
   * @return vertical center of finder pattern, or {@link Float#NaN} if not found
   */
  private crossCheckVertical(startI: number /*int*/, centerJ: number /*int*/, maxCount: number /*int*/,
      originalStateCountTotal: number /*int*/): number/*float*/ {
    const image: BitMatrix = this.image

    const maxI = image.getHeight()
    const stateCount: Int32Array = this.getCrossCheckStateCount()

    // Start counting up from center
    let i = startI
    while (i >= 0 && image.get(centerJ, i)) {
      stateCount[2]++
      i--
    }
    if (i < 0) {
      return NaN
    }
    while (i >= 0 && !image.get(centerJ, i) && stateCount[1] <= maxCount) {
      stateCount[1]++
      i--
    }
    // If already too many modules in this state or ran off the edge:
    if (i < 0 || stateCount[1] > maxCount) {
      return NaN
    }
    while (i >= 0 && image.get(centerJ, i) && stateCount[0] <= maxCount) {
      stateCount[0]++
      i--
    }
    if (stateCount[0] > maxCount) {
      return NaN
    }

    // Now also count down from center
    i = startI + 1
    while (i < maxI && image.get(centerJ, i)) {
      stateCount[2]++
      i++
    }
    if (i === maxI) {
      return NaN
    }
    while (i < maxI && !image.get(centerJ, i) && stateCount[3] < maxCount) {
      stateCount[3]++
      i++
    }
    if (i === maxI || stateCount[3] >= maxCount) {
      return NaN
    }
    while (i < maxI && image.get(centerJ, i) && stateCount[4] < maxCount) {
      stateCount[4]++
      i++
    }
    if (stateCount[4] >= maxCount) {
      return NaN
    }

    // If we found a finder-pattern-like section, but its size is more than 40% different than
    // the original, assume it's a false positive
    const stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
        stateCount[4]
    if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= 2 * originalStateCountTotal) {
      return NaN
    }

    return FinderPatternFinder.foundPatternCross(stateCount) ? FinderPatternFinder.centerFromEnd(stateCount, i) : NaN
  }

  /**
   * <p>Like {@link #crossCheckVertical(int, int, int, int)}, and in fact is basically identical,
   * except it reads horizontally instead of vertically. This is used to cross-cross
   * check a vertical cross check and locate the real center of the alignment pattern.</p>
   */
  private crossCheckHorizontal(startJ: number /*int*/, centerI: number /*int*/, maxCount: number /*int*/,
      originalStateCountTotal: number /*int*/): number/*float*/ {
    const image: BitMatrix = this.image

    const maxJ = image.getWidth()
    const stateCount: Int32Array = this.getCrossCheckStateCount()

    let j = startJ
    while (j >= 0 && image.get(j, centerI)) {
      stateCount[2]++
      j--
    }
    if (j < 0) {
      return NaN
    }
    while (j >= 0 && !image.get(j, centerI) && stateCount[1] <= maxCount) {
      stateCount[1]++
      j--
    }
    if (j < 0 || stateCount[1] > maxCount) {
      return NaN
    }
    while (j >= 0 && image.get(j, centerI) && stateCount[0] <= maxCount) {
      stateCount[0]++
      j--
    }
    if (stateCount[0] > maxCount) {
      return NaN
    }

    j = startJ + 1
    while (j < maxJ && image.get(j, centerI)) {
      stateCount[2]++
      j++
    }
    if (j == maxJ) {
      return NaN
    }
    while (j < maxJ && !image.get(j, centerI) && stateCount[3] < maxCount) {
      stateCount[3]++
      j++
    }
    if (j == maxJ || stateCount[3] >= maxCount) {
      return NaN
    }
    while (j < maxJ && image.get(j, centerI) && stateCount[4] < maxCount) {
      stateCount[4]++
      j++
    }
    if (stateCount[4] >= maxCount) {
      return NaN
    }

    // If we found a finder-pattern-like section, but its size is significantly different than
    // the original, assume it's a false positive
    const stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
        stateCount[4]
    if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal) {
      return NaN
    }

    return FinderPatternFinder.foundPatternCross(stateCount) ? FinderPatternFinder.centerFromEnd(stateCount, j) : NaN
  }

  /**
   * <p>This is called when a horizontal scan finds a possible alignment pattern. It will
   * cross check with a vertical scan, and if successful, will, ah, cross-cross-check
   * with another horizontal scan. This is needed primarily to locate the real horizontal
   * center of the pattern in cases of extreme skew.
   * And then we cross-cross-cross check with another diagonal scan.</p>
   *
   * <p>If that succeeds the finder pattern location is added to a list that tracks
   * the number of times each location has been nearly-matched as a finder pattern.
   * Each additional find is more evidence that the location is in fact a finder
   * pattern center
   *
   * @param stateCount reading state module counts from horizontal scan
   * @param i row where finder pattern may be found
   * @param j end of possible finder pattern in row
   * @param pureBarcode true if in "pure barcode" mode
   * @return true if a finder pattern candidate was found this time
   */
  protected handlePossibleCenter(stateCount: Int32Array, i: number /*int*/, j: number /*int*/, pureBarcode: boolean): boolean {
    const stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
        stateCount[4]
    let centerJ: number/*float*/ = FinderPatternFinder.centerFromEnd(stateCount, j)
    let centerI: number/*float*/ = this.crossCheckVertical(i, /*(int) */Math.floor(centerJ), stateCount[2], stateCountTotal);
    if (!isNaN(centerI)) {
      // Re-cross check
      centerJ = this.crossCheckHorizontal(/*(int) */Math.floor(centerJ), /*(int) */Math.floor(centerI), stateCount[2], stateCountTotal)
      if (!isNaN(centerJ) &&
          (!pureBarcode || this.crossCheckDiagonal(/*(int) */Math.floor(centerI), /*(int) */Math.floor(centerJ), stateCount[2], stateCountTotal))) {
        const estimatedModuleSize: number/*float*/ = stateCountTotal / 7.0
        let found: boolean = false
        const possibleCenters = this.possibleCenters
        for (let index = 0, length = possibleCenters.length; index < length; index++) {
          const center: FinderPattern = possibleCenters[index]
          // Look for about the same center and module size:
          if (center.aboutEquals(estimatedModuleSize, centerI, centerJ)) {
            possibleCenters[index] = center.combineEstimate(centerI, centerJ, estimatedModuleSize)
            found = true
            break
          }
        }
        if (!found) {
          const point: FinderPattern = new FinderPattern(centerJ, centerI, estimatedModuleSize)
          possibleCenters.push(point)
          if (this.resultPointCallback !== null && this.resultPointCallback !== undefined) {
            this.resultPointCallback.foundPossibleResultPoint(point)
          }
        }
        return true
      }
    }
    return false
  }

  /**
   * @return number of rows we could safely skip during scanning, based on the first
   *         two finder patterns that have been located. In some cases their position will
   *         allow us to infer that the third pattern must lie below a certain point farther
   *         down in the image.
   */
  private findRowSkip(): number /*int*/ {
    const max = this.possibleCenters.length
    if (max <= 1) {
      return 0
    }
    let firstConfirmedCenter: ResultPoint = null
    for (const center of this.possibleCenters) {
      if (center.getCount() >= FinderPatternFinder.CENTER_QUORUM) {
        if (firstConfirmedCenter == null) {
          firstConfirmedCenter = center
        } else {
          // We have two confirmed centers
          // How far down can we skip before resuming looking for the next
          // pattern? In the worst case, only the difference between the
          // difference in the x / y coordinates of the two centers.
          // This is the case where you find top left last.
          this.hasSkipped = true
          return /*(int) */Math.floor((Math.abs(firstConfirmedCenter.getX() - center.getX()) -
              Math.abs(firstConfirmedCenter.getY() - center.getY())) / 2)
        }
      }
    }
    return 0
  }

  /**
   * @return true iff we have found at least 3 finder patterns that have been detected
   *         at least {@link #CENTER_QUORUM} times each, and, the estimated module size of the
   *         candidates is "pretty similar"
   */
  private haveMultiplyConfirmedCenters(): boolean {
    let confirmedCount = 0
    let totalModuleSize: number/*float*/ = 0.0
    const max = this.possibleCenters.length
    for (const pattern of this.possibleCenters) {
      if (pattern.getCount() >= FinderPatternFinder.CENTER_QUORUM) {
        confirmedCount++
        totalModuleSize += pattern.getEstimatedModuleSize()
      }
    }
    if (confirmedCount < 3) {
      return false
    }
    // OK, we have at least 3 confirmed centers, but, it's possible that one is a "false positive"
    // and that we need to keep looking. We detect this by asking if the estimated module sizes
    // vary too much. We arbitrarily say that when the total deviation from average exceeds
    // 5% of the total module size estimates, it's too much.
    const average: number/*float*/ = totalModuleSize / max
    let totalDeviation: number/*float*/ = 0.0
    for (const pattern of this.possibleCenters) {
      totalDeviation += Math.abs(pattern.getEstimatedModuleSize() - average)
    }
    return totalDeviation <= 0.05 * totalModuleSize;
  }

  /**
   * @return the 3 best {@link FinderPattern}s from our list of candidates. The "best" are
   *         those that have been detected at least {@link #CENTER_QUORUM} times, and whose module
   *         size differs from the average among those patterns the least
   * @throws NotFoundException if 3 such finder patterns do not exist
   */
  private selectBestPatterns(): FinderPattern[] /*throws NotFoundException */ {

    const startSize = this.possibleCenters.length
    if (startSize < 3) {
      // Couldn't find enough finder patterns
      throw new Exception(Exception.NotFoundException)
    }
    
    const possibleCenters = this.possibleCenters

    let average: number/*float*/
    // Filter outlier possibilities whose module size is too different
    if (startSize > 3) {
      // But we can only afford to do so if we have at least 4 possibilities to choose from
      let totalModuleSize: number/*float*/ = 0.0
      let square: number/*float*/ = 0.0
      for (const center of this.possibleCenters) {
        const size: number/*float*/ = center.getEstimatedModuleSize()
        totalModuleSize += size
        square += size * size
      }
      average = totalModuleSize / startSize
      let stdDev: number/*float*/ = /*(float) */Math.sqrt(square / startSize - average * average)

      possibleCenters.sort(
        /**
         * <p>Orders by furthest from average</p>
         */
        // FurthestFromAverageComparator implements Comparator<FinderPattern>
        (center1: FinderPattern, center2: FinderPattern) => {
          const dA: number/*float*/ = Math.abs(center2.getEstimatedModuleSize() - average)
          const dB: number/*float*/ = Math.abs(center1.getEstimatedModuleSize() - average)
          return dA < dB ? -1 : dA > dB ? 1 : 0
        })

      const limit: number/*float*/ = Math.max(0.2 * average, stdDev);

      for (let i = 0; i < possibleCenters.length && possibleCenters.length > 3; i++) {
        const pattern: FinderPattern = possibleCenters[i]
        if (Math.abs(pattern.getEstimatedModuleSize() - average) > limit) {
          possibleCenters.splice(i, 1)
          i--
        }
      }
    }

    if (possibleCenters.length > 3) {
      // Throw away all but those first size candidate points we found.

      let totalModuleSize: number/*float*/ = 0.0
      for (const possibleCenter of possibleCenters) {
        totalModuleSize += possibleCenter.getEstimatedModuleSize()
      }

      average = totalModuleSize / possibleCenters.length

      possibleCenters.sort(
        /**
         * <p>Orders by {@link FinderPattern#getCount()}, descending.</p>
         */
        // CenterComparator implements Comparator<FinderPattern>
        (center1: FinderPattern, center2: FinderPattern) => {
            if (center2.getCount() === center1.getCount()) {
              const dA: number/*float*/ = Math.abs(center2.getEstimatedModuleSize() - average)
              const dB: number/*float*/ = Math.abs(center1.getEstimatedModuleSize() - average)
              return dA < dB ? 1 : dA > dB ? -1 : 0
            } else {
              return center2.getCount() - center1.getCount()
            }
        })

      possibleCenters.splice(3)// this is not realy necessary as we only return first 3 anyway
    }

    return [
        possibleCenters[0],
        possibleCenters[1],
        possibleCenters[2]
    ]
  }
}
